time bomb

A subspecies of logic bomb that is
triggered by reaching some preset time, either once or
periodically. There are numerous legends about time bombs set up
by programmers in their employers' machines, to go off if the
programmer is fired or laid off and is not present to perform the
appropriate suppressing action periodically.

Interestingly, the only such incident for which we have been
pointed to documentary evidence took place in the Soviet Union in
1986! A disgruntled programmer at the Volga Automobile Plant
(where the Fiat clones called Ladas were manufactured) planted a
time bomb which, a week after he'd left on vacation, stopped the
entire main assembly line for a day. The case attracted lots of
attention in the Soviet Union because it was the first cracking
case to make it to court there. The perpetrator got a suspended
sentence of 3 years in jail and was barred from future work as a
programmer.

An explosive that is rigged to explode at a preset time. Time bombs can be detonated by pretty much any type of clock, mechanical or electronic. One way to create a time bomb would be to have a detonation switch that is closed by the minute-hand when it reaches a certain point.